Electroresponsive control system



Jan. 10,1939. AM|LL| 2,143,684

I ELECTRORESPONSIVE CONTROL SYSTEM v Filed July 31, 1936 Irivehtor:Guglielmo jyamilli, b V 1M1 Patented Jan. 10, 1939 PATENT orrics2,148,884 HBCTBORE SPONSIVE CONTROL SYSTEM anus... Camilli, manna, ms...assignm- General Electric Company, a corporation at New York ApplicationJilly 31, 1936, Serial No. 93,562 I 7 Claims. (01. 171-119) My inventionrelates to electro-responsive control systems and more particularly toimprovements in voltage-responsive control systems utilizing glow tubes.

Eiectro-responsive control systems are adapted for use in arrangementsfor indicating, controlling and regulating various operating conditionssuch as current, voltage, pressure, temperature and numerous othersimilar conditions. While my invention is capable of quite generalapplication and it is not intended that it be limited to any particularapplication, it is particularly suitable an automatic voltage regulatingsystem. The most common type of voltage sensitive main control means foran automatic voltage regulating system is an electro-magnetic relay orcontact making voltmeter which has a coil connected to respond to thevoltage to be regulated and this coil acts on an armature or solenoidcore which actuates a contact making member. Two of the most importantdisadvantages of such an arrangement are that no positive contacts aremade, especially when the voltage is slightly different from ,the normalvalue and the apparatus is as delicate as an ordinary measuringinstrument and requires the same careful handling and maintenance. 7

In the circuit of my invention these disadvantages have been eliminated,the circuit being relatively rugged and making and breaking contactspositively in response to very slight changes in voltage. The mainvoltage-sensitive element of my circuit is a glow tube. Such a tubeconsists of an envelope containing two electrodes and a suitable gas,such as neon, the pressure 0! which is reduced to the point of minimumimpedance. It is well known that the voltage at which such a tube breaksdown and passes current is remarkably constant and is largelyindependent of frequency and temperature.

- An object of my invention is to provide a new and improvedelectro-responsive control system.

Another object of my invention is to provide a rugged and positivelyactuated voltage-sensitive control system.

A further object of my invention is to-provide a novel voltage-sensitivecircuit controlled by a glow tube.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

Referring now to the single figure of the accompanying drawing, I haveshown therein diaas a main voltage responsive control means forgrammatically, by way of example, an embodiment of my invention forcontrolling an automatic voltage regulating system for a main elec triccircuit I. My voltage-sensitive control system comprises a pair ofcontrol relays 2 and 3 5 the contacts 01' which, together with thecontacts or a differential relay 4, complete control circuits whichdetermine the direction of operation of a motor 5 for operating aregulator O for the voltage of circuit I. Regulator E may be of anysuitable in and well known type and is shown by way of example as aninduction voltage regulator. The proper energization of the controlrelays I and 3 and the differential relay 4 in response to changes involtage of circuit I is controlled by a sensitive i5 relay I under thecontrol of aglow tube 8. Relays 2 and 3 are normally open relays in thesense that their contacts are open when they are deenergized. Relay I,which is the only relay which needs to have a sensitive setting oradjustment, 0 is a normally closed relay. Diflerential relay 4 has apair of opposed windings which are so arranged that when they are bothenergized the contacts of the relay are open and when either one isenergized alone the contacts or the relay 25 are closed. Relay 2, whichis arranged to be closed when the voltage of circuit I is low and whichconsequently may be referred to as the raise" relay because it controlsthe operation of the regulator to raise the voltage, has its operatingwinding connected across the circuit I in series with one of thewindings or the diilerential relay l and the contacts of the sensitiverelay I. Relay 3, which is arranged to be energized when the voltage ofthe circuit I is high and which consequently may be referred to as thelower" relay because it controls the operation of the regulator to lowerthe voltage, has its operating winding connected across the circuit I inseries with the glow tube 8, the remaining winding of 40 thediiIerential relay 4 and the operating winding of the sensitive relay"I.

The operation of the illustrated embodiment of my invention is asfollows: Let it be assumed that it is desired to maintain the voltage ofcir- 5 cult I between 110 and 110% volts. For such regulation a glowtube 8 is selected which breaks down when the voltage of circuit l is110 volts I and the relay I is so adjusted that it does not open itscontacts until the voltage of circuit I is 110% volts. Assume now thatthe voltage across circuit I is only 108 volts. Under these conditionscurrent flows through the raise relay 2, through one of the windings ofthe difierential relay 4 and through the normally closed contacts of therelay 1. This causes raise" relay 2 and diflerential relay 4 to closetheir contacts, which are in series in a circuit including the motor 5and a suitable source of operating current for the motor such as acontrol battery. 5. This causes themotor 5 to operate in such directionas to cause the regulator 6 to raise the voltage of circuit 1. When thevoltage becomes 110 volts the glow tube 8 breaks down causing current toflow through the operating-winding of "lower relay 3, the remainingwinding of the differential relay 4 and the operating-winding of thesensitive relay I. This causes lower relay 3 to close its contacts andcauses differential relay 4 to open its contacts because both of itswindings are'now operatively energized. Consequently, although both theraise relay 2 and the lower relay 3 are now closed the opening of thecontacts of the differential relay 4 prevents the completion of eitherof the control circuits for the motor 5 and therefore the motor comes torest and the regulator ceases to change the voltage of circuit 5. It nowthe voltage of, circuit I should increase, from any cause such as areduction; in load thereon or an increase in the voltage of the sourceof supply for this circuit, and this increase should exceed 110 voltsthe sensitive relay 1 would open its contacts. This would causedeenergization of the "lower relay 2 and of the uppermost one of the twowindings of the differential relay 5. Consequently, relays 3 and 4 wouldnow be closed and as their contacts are in series in a circuit, with themotor 5 and the source 9, for causing reverse operation of the motor 5the regulator will act -to lower the voltage of circuit I.

It will thus be seen'that my system automatically responds to changes ofvoltage in circuit i in such a manner that below a certain voltage valueone control circuit is. controlled, above another voltage value theother control circuit is controlled and between both voltage values bothcontrol circuits are unchanged. By the term controlled I mean to includeboth the ordinary circuit opening or circuit closing type of control aswell as the well known variable efiective impedance type of control. Thetwo voltage values may also be considered as defining a range or zone ofvoltage insensitivity above or below which the control circuits areselectively controlled. Furthermore, from another point of view, it willbe seen that the two control circuits are selectively controlled whenthe voltage is above or below a predetermined value, corresponding tohalf way lay providedwith between 'the two above-mentioned voltagevalues,

by a predetermined amount, corresponding to half the difference betweensaid voltage values, in either direction, respectively' Thepredetermined voltage valuemay be considered as the normal voltage valuefor the main regulated circuit. v

While I have shown and described a particular embodiment of myinvention, it will be obvious to. those skilled in the art thatcha'ngesand modifications can be made therein and I, thereiore,'aim inthe appended claims to cover all such changes and modifications asfallwithin the true spirit and scope of my invention.

What I claim as'new. and. desire 'tosecure by Letters Patent or theUnited States is:

1. In a voltage sensitive control system, -in combination, an electriccircuit, a difierential re-, opposed actuating elements and having anactuated and a de-actuated condition, and means including a glow tubeand a. voltage sensitive relay for-actuating said serially coh- -lysensitive relay having an operating winding and a set of contacts, adifferential relay having two windings, and a glow tube connected acrosssaid circuit in series with the winding of saidsensitive relay and oneof the windings of said difierential relay, the other winding of saiddifferential relay being connected across said circuit I in series withthe contacts of said sensitiverelay.

3. In,combination', an electric circuit, a normally closed relativelysensitive relay having an operating winding and a set of contacts, adif: ferential relay having two windings, and a glow tube'connectedacross said circuit in series with the winding of said sensitive relayand one of the windings of said diilerential relay, the other wind-..

ing of said differential relay being connected across said circuit inseries with the contacts of said sensitive relay, said sensitive relaybeing set to open its contacts at a current appreciably higher than thecurrent corresponding to the minimum voltage required to break down saidglow tube whereby at low and high values of voltage of said circuit thedifferential relay is actuated and at intermediate values oi. voltage ofsaid circuit said difierential relay is deactuated.

4. In combination, an electric circuit, a relatively sensitive relayhaving an operating winding and a set of contacts, a differential relayhaving two windings, a glow tube connected across said circuit in serieswith the winding of said sensitive relay and one of the windings of saiddiflerential relay, the other winding of said diflerential relay beingconnected across said circuit in series with the contacts of saidsensitive relay, said sensitive relay being set to open its contacts ata current appreciably higher than the current corresponding to theminimum voltage required to break down said glow tube whereby at low andhigh voltages of said electric circuit the diflerential relay isactuated and at intermediate values of voltage of said electriccircuit'said differential relay is de-actuated, and control circuitscontrolled by said difierential relay.

5. A voltage-sensitive control system comprising, in combination, anelectric circuit, two normally open control relays, a difierential,relay having two windings, a normally closed sensitive relay, a glowtube, a connection across said circult including the operating windingof one of said control relays, one .o! the windings of said differentialrelay and the contacts of said sensitive relay in series, anotherconnection across said circuit including said glow tube, the winding ofthe other control relay, the remaining winding of said diflerentialrelay and the winding'of said sensitive relay in series, said sensitiverelay being set to open its contacts at a current'appreclably higherthan the current corresponding to a value I of voltage of said circuitwhich is just'suiilcient to break down said glow tube whereby when the"energized and its contacts open, and separate control circuits eachincluding the contacts 01 one of said control relays and both includingthe contacts oi said differential 6. A voltage-sensitive systemcomprising, in combination, a main circuit, a pair of normally opensecondary circuits adapted respectively to be closed when the voltage ofsaid main circuit has different predetermined values, a glow tubeconnected to be responsive to the voltage of said main circuit andhaving the characteristic of breaking down from a non-conducting to aconducting state at a fixed voltage which is between said values, meansresponsive to the absence of current in said glow tube for-closing oneof said secondary circuits, means responsive to the breakdown of saidglow tube for opening said closed secondary circuit, and meansresponsive to a predetermined increase in current through said glow tubefor closing the other of said secondary circuits.

7. An automatic voltage regulator system comprising, in combination, amain circuit whose Patent so. 2,11 ,681

voltage is to be regulated, a pair of normally open voltage raise andlower circuits adapted respectively to be closed when the voltge of saidmain circuit has predetermined low and high values, a glow tubeconnected to be responsive to the voltage of said main circuit andhaving the characteristic of breaking down from a non-conducting to aconducting current at a fixed voltage January 10, 1959.

GUGLIELHO CAHILLI It is hereby certified that error appears in theprinted specification of theabove mimbered patent requiring correctionas follows: Page I, second column, line k6, after the numeral "110"insert the word volts; page 2, first column, line 75, claim 1, strikeout the words "for actmiting said" endinsert'the came before"differential", second column, line 1, same claim;- and that the saidLetters Patent shouldbe read with this correction therein that the rice.

same inay conform to the record of the case in the Patent Of- Signed andsealed. this 28th day of February, A.D. 1959.

Henry Van Arsdale Acting Commissioner of Patents.

